It has long been recognized that airborne bacteria and other airborne contaminants in the operating room are a primary cause of post operative infection. This is particularly true with operations which are long in duration and/or where the wound or incision covers a large surface area.
The prefiltering of air supplied to the operating room is insufficient to adequately reduce airborne contaminants, and various systems have been introduced to deliver clean air to an operating room, and remove air from the operating room, in a manner which effectively removes airborne particulates. Such systems generally rely on delivering large quantities of air to the center of the operating room such that air pressure within an operative zone therein, is greater than the pressure outside of the zone, so as to keep contaminants out. In most conventional systems, this prefiltered air is introduced through ducts and registers in the ceiling such that a vertical flow of air is forced downwardly upon the operating table and the operating area surrounding it creating a clean air zone from which contaminants are flushed.
One of the primary sources of airborne contaminants is the surgical team and other persons within the operating room. In this regard, contaminants are entrained into the operating region of the operating room as members of the surgical team move into and out of the operating region. Further, there is a natural tendency for airborne contaminants to rise into the zone above the operating table due to heat from surgical lights and the surgical team. Moreover, contaminants collected on ceiling, floor and wall surfaces and on equipment, subsequently become airborne and a source of infection. Also, such ceiling mounted systems occupy large portions of the ceiling area and generally are mounted in a suspended ceiling having removable ceiling panels such that the system can be accessed for maintenance and repair. Accordingly, ceiling space is lost which could otherwise be used for supporting medical equipment, and the suspended ceilings tend to collect contaminants and are difficult to clean. Moreover, the vertical flow of air is often disrupted by surgical lights and other equipment thereby compromising the clean air zone.
Other air handling systems utilize a horizontal air flow pattern whereby laminar or near-laminar air flow is directed horizontally across the operating room flushing the operating area with clean air. Such horizontal flow systems, when unobstructed, provide an efficient means for sweeping the operating area free of contaminants, but medical equipment can disrupt the flow unless restrictions are placed on equipment placement. Further, substantial amounts of wall space must be dedicated to such systems.
An example of one air handling system which utilizes a diagonal air flow pattern is disclosed in U.S. Pat. No. 3,150,584, issued to C. Allander However, the Allander system creates an air current over a portion of the room which is inadequate for maintaining the entire operating zone or region free of contaminants. Another system which utilizes a diagonal air flow pattern is disclosed in U.S. Pat. No. 4,781,108, issued to Nillson, but the Nillson system utilizes a combination of diagonal and horizontal air currents which intersect. These intersecting air currents result in turbulence which disrupts the desired sweeping action of the air flow through the operating region.
Examples of other air flow handling devices are disclosed in U.S. Letters Pat. Nos. 2,847,928; 3,838,556; 3,908,155; 3,948,155; 4,020,752; and 4,598,631. Also, examples of vertical and horizontal air flow systems are disclosed in "Contamination-Free Environments for the Microelectronics Industry", by Ed Cook, Microcontamination, June 1987. Moreover, systems are disclosed in Canadian Patent Number 696,314, and Japanese Patent Numbers 282,742; 138,636; and 190,337. The Japanese '337 patent is similar to that of the U.S. '108 patent except that the only return is on the floor below the inlet on the same side of the room. Thus, there is no diagonal "sweeping" of the room. This system is designed to cover a work table underneath the unit and not the entire room.
Therefore, it is an object of the present invention to provide an improved air handling system and method for supplying HEPA (99.97% of 0.3 microns and larger) filtered air to an operating room in a manner which reduces the concentration of airborne bacteria and contaminants within the operating room.
Another object of the present invention is to provide an improved air handling system which does not occupy large areas of the walls and ceiling of the operating room.
Still another object of the present invention is to provide an air handling system which creates an air flow pattern which has minimum disruption by surgical lights and other equipment within the operating room, and which improves comfort of the surgical staff.
A further object of the present invention is to provide an air handling system for an operating room which produces sufficient unidirectional air flow streams to effectively sweep the entire room.
Yet another object of the present invention is to provide an air handling system which is inexpensive to manufacture and maintain.
It is also an object to provide a system that can be constructed in modules to facilitate the air handling for rooms of different size, etc.